Karst Features in the Black Hills, Wyoming and South Dakota- Prepared for the Karst Interest Group Workshop, September 2005
193 INTRODUCTION TO THREE FIELD TRIP GUIDES: Karst Features in the Black Hills, Wyoming and South Dakota- Prepared for the Karst Interest Group Workshop, September 2005 By Jack B. Epstein1 and Larry D. Putnam2 1U.S. Geological Survey, National Center, MS 926A, Reston, VA 20192 2Hydrologist, U.S. Geological Survey, 1608 Mountain View Road, Rapid City, SD 57702. This years Karst Interest Group (KIG) field trips will demonstrate the varieties of karst to be seen in the semi-arid Black Hills of South Dakota and Wyoming, and will offer comparisons to karst seen in the two previous KIG trips in Florida (Tihansky and Knochenmus, 2001) and Virginia (Orndorff and Harlow, 2002) in the more humid eastern United States. The Black Hills comprise an irregularly shaped uplift, elongated in a northwest direction, and about 130 miles long and 60 miles wide (figure 1). Erosion, following tectonic uplift in the late Cretaceous, has exposed a core of Precambrian metamorphic and igneous rocks which are in turn rimmed by a series of sed- iments of Paleozoic and Mesozoic age which generally dip away from the center of the uplift. The homocli- nal dips are locally interrupted by monoclines, structural terraces, low-amplitude folds, faults, and igneous intrusions. These rocks are overlapped by Tertiary and Quaternary sediments and have been intruded by scattered Tertiary igneous rocks. The depositional environments of the Paleozoic and Mesozoic sedimen- tary rocks ranged from shallow marine to near shore-terrestrial. Study of the various sandstones, shales, siltstones, dolomites and limestones indicate that these rocks were deposited in shallow marine environ- ments, tidal flats, sand dunes, carbonate platforms, and by rivers.
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